Unauthorized return status

[TJISMH]

After many months of no issues using the API development, I noticted unauthorized errors in our log files to day on our test user when fetching activity data.

So I sent that user back thru the OAUTH process to get a new access token. Everything works fine and I get the access token but when trying to create a subscription for the user using the new access token I am getting an unauthorized.

What might this be indicative of?

[ibahdanau]

The only case when you can be deauthorized is when you request for new access token. 

So new acecss token becomes active anv valid and previous got expired.

Please check that in your code you don't request for new access token when you execut subscribe API request.

[Doug]

Did you change your app from read-only to read/write access or vice versa?  I believe doing so would invalidate all existing user authorizations and make them re-authorize you app.  Might change your own keys too, though I am not sure of that.